Peanut Weed Control Update - July 22 (Prostko)

 I thought you might be interested in a few pictures from our peanut weed control plots taken earlier today.

A few comments: 

1) UGA's recommended weed control program [a) starting clean, b) planting in twin rows, c) using multiple residuals at planting that get activated by irrigation and/or rainfall, and d) making timely (34 DAP) POST applications] looks very good as usual.  This location has received 14.12" of rainfall since May 1 (3.56" above average) and the residual herbicides have lasted longer than anticipated.  

2) Once again, I see no significant differences in weed control between Prowl or Sonalan-based weed control programs.

3) The only tweeks to this program would be the addition of either Cobra or Ultra Blazer to the Cadre + 2,4-DB + Dual Magnum POST treatment.  Also, could use other Group 15 herbicides depending upon grower preference (Anthem Flex, Outlook, Warrant, Zidua).  Remember, Cobra has performed better on larger pigweeds than Ultra Blazer.

4) Generally, peanut growers have all the tools that they need for weed control (except for perennial broadleaf weeds).  Just have to figure out a better way for them to be more timely?  

Carpetweed in Peanut (Prostko)

I have been getting lots of questions recently about the control of carpetweed (Mollugo verticillata) in peanut.  Check out these pictures from Ben Reeves (Berrien Co.) who sent them to me earlier today. 

A few things to chew on:

1) Carpetweed is summer annual weed native to the U.S.

2) Other common names for this weed include green carpetweed, Indian chickweed, whorled chickweed, and devil's grip. 

3) Carpetweed is listed as a controlled weed on EVERY peanut herbicide label except for Basagran (bentazon), Butyrac (2,4-DB), Classic (chlorimuron), Strongarm (diclosulam), and the POST grass herbicides [Fusilade (fluazifop), Poast (sethoxydim), and Select (clethodim)]. So...?

4) No confirmed cases of herbicide-resistance in carpetweed have been reported worldwide. (https://www.weedscience.org/summary/species.aspx)

5) Carpetweed has been in my research plots for 15+ years.  I have never failed to control it with my recommended peanut weed control programs (http://www.gaweed.com/newest-prostko-2024-control-peanut-corn-soy.pdf).

6) Possible reasons for lack of carpetweed control in 2024 are as follows:

a) Too wet?  Residual herbicides do not last as long; growers cannot get into fields on timely basis; unexpected pop-up showers occur before rain-free period is reached. 

b) Too dry? Residual herbicides do not get activated on a timely basis; big weeds + dry weather are a POST herbicide's Achilles heel.

c) Reduced herbicide rates?  Many growers are not using full labeled rates of herbicides such as Cadre (imazapic) to help prevent carryover in 2025.  We proved many years ago that this strategy does not really work.  Cotton will find Cadre in the soil when a lab analysis will not.  More importantly, when reduced rates are used and less than 100% weed control is obtained, the evolution of herbicide-resistance is greatly increased.  Yes, we can control some weeds with reduced herbicide rates (i.e. bristly starbur/Strongarm) but this tactic does not work for every weed and every herbicide. 

An Interesting Exchange (Prostko)

Thought everyone might benefit from this recent text conversation that I had with one of the best peanut/cotton growers in the state of Georgia.  Here it is. 

Grower Question?

Do you think I can apply this product [Ag-Min (30% Mn + 15% S)] with 2,4-DB?

.  

Prostko Response:

There have been some issues in the past with Mn + DB.  See below.   Also, my colleague at NC State University (Dr. David Jordan) has seen some problems as well. Last few years some weird stuff has happened.  Might be better to co-apply with fungicide.

 

Recent NC State Blog (07/03/24): 

https://peanut.ces.ncsu.edu/2024/07/manganese-and-24-db-peanut-notes-no-135-2024/

Grower Response 1 Day Later:

So I rolled the dice.  I have the ability to circulate my mixing vat to fully dissolve dry matter.  Also, my sprayer has good agitation.  I am running 15 GPA, so probably a more diluted spray solution that most.  I still made polyester.  I am telling you, not to admit that I am an idiot for not heeding your warning, but so that you can tell others that ask.  It's absolutely a no go!

Prostko Response 1 Day Later:

At least you were wearing PPE!